The invention discloses an on-line anode connecting method and structure for prebaked anode aluminium electrolysis. The on-line anode connecting method is characterized in that carbon bowls (3) at the top of a carbon block body (1) of an anode is connected with a steel claw (2) through casting of aluminium water; when the carbon block body (1) in an electrolytic bath is burnt to the degree that connection with a new anode is required, aluminium water in the carbon bowls (3) of the old carbon block body (1) is molten, the steel claw (2) is taken out, and at the moment, the old carbon block body (1) bears through a covering material at the periphery of the carbon block and a condensation layer of an electrolyte; a new carbon block body (1) is placed above the old carbon block body (1); the new carbon block body (1) and the old carbon block body (1) are connected through a fixing convex head (4) at the bottom of the new carbon block body (1) and the carbon bowls (3) of the old carbon block body (1); and the steel claw (2) is fixed in the carbon bowls (3) of the new carbon block body (1) through casting of aluminium water. According to the application, the structures of the steel claw and the anode carbon blocks are further simplified, the modification cost is lowered, and the use is more convenient.